I took a DVD that someone had made with a standalone burner and decided that the video could use some cleaning up.

I plugged the VOBs into DVD2AVI and separated out the audio, ending up with the d2v file and a 256k ac3 file.

I put the d2v into TMPGEnc 2.5+ for its noise reduction and a few other enhancements. The resulting m2v file looked fantastic.

I went into DVD Author Pro to match the m2v and ac3 files back up, add chapters and create a new DVD from it all.

The problem is that though the audio starts out in perfect sync, as the video goes along (it is 65 minutes total) the sound slowly goes out of sync. By the end it is about maybe a half second off!

What happened? Did reencoding the video magically add or drop enough milliseconds of time to accumulate cause this problem? It was VBR before, and I used CBR for the reencode. Something with the I/P/Bs? What an odd problem!

I am only using DVD2AVI and TMPGEnc. I am not sure if you are familiar with how to use DVD2AVI to get the information to plug into TMPGEnc, but that is all I did, no AVI file was involved. TMPGEnc 2.5 does not accept straight VOB files the way 3.0 and up do, but if you have a better way to do it you have my attention.

DVD2AVI reports the original VOBs's frame rate is 29.970. This was the setting I used in TMPGEnc previously in the Video Stream settings.
What is odd is the text info file included as part of the DVD says "Frame Rate: 30.00," so I guess I will give it another shot with the "no frame rate conversion" setting you suggest. I am not sure why DVD2AVI would report a bogus frame rate, though.

The AC3 file says it is three seconds longer than the original m2v file I ended up with.

I reencoded with TMPGEnc with the frame rate set at 30fps and "no frame rate conversion" selected. I again went to DVD Author Pro to try to make a DVD, and it will not accept the m2v file because it is not NTSC (29.97) standard. So I guess I am out of luck and will have to allow TMPGEnc to do a frame rate conversion?

I'm not entirely convinced the original DVD is 30fps, really. If I use Source Wizard in DVD Author and bring in the original DVD as-is, it loads it up properly and says it is 29.97. I wonder if DVD2AVI is somehow not extracting the ac3 file correctly?

When you selected "no frame rate conversion", did you set the output frame rate to 29.97? If so, the file should be perfectly "legal".

Anyway, if you can't get that to work, you could try changing the duration of the the AC3 file to match the M2V (if you have any audio processing software). It will force you to reencode the sound, but it's probably better than having the sync problem.

Wouldn't what have happened the first time? I'm asking if, the second time, when you checked "no frame rate conversion", you set the frame rate to 29.97.

I assume that was the frame rate the first time, but then you didn't have the "no frame rate conversion" box checked.

Yes, the very first time I tried the encode, I had the frame rate set to 29.97 but "no frame rate conversion" was not checked. So I assumed that no matter what the source's fps was, it would have been converted to 29.97.

The second time I set the frame rate to 30fps and selected No frame rate conversion."

So should I try setting the frame rate to 29.97 and selecting no conversion? That is confusing.